Pixel structure and oled display panel

ABSTRACT

A pixel structure and an organic light-emitting diode (OLED) display panel incorporating the pixel structure are disclosed. The pixel structure includes a plurality of pixel units (110) arranged in an array, each pixel unit comprising a first sub-pixel (111), a second sub-pixel (112) and a third sub-pixel (113). The second sub-pixel (112) and the third sub-pixel (113) are common to four adjacent pixel units (110). As a result, a higher aperture ratio of the sub-pixels, an increased design margin and reduced process difficulty can be obtained.

TECHNICAL FIELD

The present invention relates to the field of display technology and, inparticular, to a pixel structure and an organic light-emitting diode(OLED) display panel incorporating the pixel structure.

BACKGROUND

Organic light-emitting diode (OLED) display panels are considered to bethe most potential next generation of new flat panel display technologythanks to their wide variety of outstanding advantages including activeillumination, slimness, a large viewing angle, fast response, goodenergy-saving performance, a wide temperature tolerance range andcapabilities of flexible and transparent display.

There have been well developed insofar two full-color techniques forOLED display panels: color filters (CF) and RGB (the three primarycolors: red, green and blue) pixels.

Like those used in liquid crystal display (LCD) panels, color filterscan also be used in OLED display panels for the full-color effect. Inthese cases, white-light OLEDs serve as backlight playing the same roleas both backlight and liquid crystal molecules in LCD panels, and colorfilters are placed thereon to form red, green and blue sub-pixels. Inthis way, the resolution and large panel requirements can be satisfied.However, as light loses significant energy when passing through thecolor filters, such display panels suffer from significant powerconsumption.

In order to address the high power consumption issue, full-color OLEDdisplay panels using RGB pixels have been developed.

FIG. 1 schematically illustrates an existing OLED display panelutilizing RGB pixels. As shown in FIG. 1, the OLED display panel isformed in a paralleled RGB manner and has multiple pixel units Pixeleach including, horizontally aligned, one red sub-pixel unit R, onegreen sub-pixel unit G and one blue sub-pixel unit B. The sub-pixelunits in the OLED display panel are arranged in a matrix and each ofthem has a display section 1 and a non-display section 2. Specifically,the display section 1 of each sub-pixel unit is provided with a cathode,an anode and an electroluminescent layer (organic emission layers)disposed therebetween to generate light of the prescribed color so as toenable the display of an image. The electroluminescent layer is usuallyfabricated by vapor deposition. During the fabrication of theconventional display panel, three vapor deposition processes are carriedout to form electroluminescent layers for the corresponding colors (red,green and blue) in the display sections 1 of the pixel units.

FIG. 2 schematically illustrates another existing OLED display panelutilizing RGB pixels. As shown in FIG. 2, the OLED display panel formedin an RGB matrix manner has multiple pixel units Pixel each includingone red sub-pixel unit R, one green sub-pixel unit G and one bluesub-pixel unit B. Two out of these three sub-pixel units, for example,the red sub-pixel unit R and the green sub-pixel unit G are arranged ina column, and the third sub-pixel unit, for example, the blue sub-pixelunit B, is disposed in another column. As such, the sub-pixel units inthe OLED display panel are arranged in a matrix.

As technology evolves, users are increasingly demanding for OLED displaypanels with higher resolution, and the conventional RGB pixelarrangements have fallen short in meeting the increasingly higher PPI(pixels per inch) requirements.

SUMMARY OF THE INVENTION

The present invention provides a pixel structure, comprising a pluralityof pixel units arranged in an array, each pixel unit comprising a firstsub-pixel, a second sub-pixel and a third sub-pixel, the second andthird sub-pixels being common to four adjacent ones of the pixel units.

In one embodiment, adjacent four third sub-pixels may be arranged todefine a quadrilateral encompassing one second sub-pixel and adjacentfour first sub-pixels so that four pixel units are formed in which eachof the four first sub-pixels is located between the second sub-pixel anda corresponding one of the four third sub-pixels.

In one embodiment, each first sub-pixel may reside on a line segmentconnecting centers of its adjacent second and third sub-pixels.

In one embodiment, the first, second and third sub-pixels may all bepolygons.

In one embodiment, the first, second and third sub-pixels may bequadrilaterals, hexagons, octagons or any combination thereof.

In one embodiment, the first sub-pixel may be a rectangle, with each ofthe second and third sub-pixels being a square.

In one embodiment, short sides of each first sub-pixel may be parallelto a line segment connecting centers of its adjacent second and thirdsub-pixels. Alternatively, the short sides of each first sub-pixel maybe perpendicular to a line segment connecting centers of its adjacentsecond and third sub-pixels.

In one embodiment, the first, second and third sub-pixels in one pixelunit may be symmetric to corresponding ones in an adjacent unit.

In one embodiment, the first sub-pixel may have an area smaller than anarea of the second and third sub-pixels.

The present invention also provides an organic light-emitting diode(OLED) display panel comprising a pixel structure as defined above.

In order to solve the problem described above, the present inventionprovides a pixel structure for use in an OLED display panel, in whicheach pixel unit includes a first sub-pixel, a second sub-pixel and athird sub-pixel, and the second and third sub-pixels are common to fouradjacent pixel units. As a result, a higher aperture ratio of thesub-pixels can be obtained at the same PPI and design margin.Alternatively, an increased design margin and reduced process difficultycan be obtained at the same PPI and aperture ratio.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates part of a pixel structure in anexisting organic light-emitting diode (OLED) display panel.

FIG. 2 schematically illustrates part of a pixel structure in anotherexisting OLED display panel.

FIG. 3 is a schematic showing part of a pixel structure in an OLEDdisplay panel according to a first embodiment of the present invention.

FIG. 4 is a schematic illustration of four pixel units in the pixelstructure of FIG. 3.

FIG. 5 is a schematic showing part of a pixel structure in an OLEDdisplay panel according to a second embodiment of the present invention.

FIG. 6 is a schematic illustration of four pixel units in the pixelstructure of FIG. 5.

FIG. 7 is a schematic showing part of a pixel structure in an OLEDdisplay panel according to a third embodiment of the present invention.

FIG. 8 is a schematic illustration of four pixel units in the pixelstructure of FIG. 7.

DETAILED DESCRIPTION

As described in the Background section, the conventional RGB pixelarrangements have fallen short in meeting the increasingly higher PPIrequirements. In view of this, it is proposed in the present invention apixel structure for an organic light-emitting diode (OLED) displaypanel, comprising a plurality of pixel units arranged in an array, eachincluding a first sub-pixel, a second sub-pixel and a third sub-pixel.The second and third sub-pixels are common to four adjacent pixel units.This arrangement allows a higher aperture ratio of the sub-pixels and alonger life span of the display device at the same PPI and designmargin, or an increased design margin, reduced process difficulty and animproved yield at the same PPI and aperture ratio.

Presented above is the basis concept of the present application. Thesubject matter of specific embodiments of the present invention will befully described with reference to the drawings accompanying theembodiments so that it will be more apparent. Obviously, the disclosedembodiments are only some rather than all embodiments of the invention.All other embodiments made by those of ordinary skill in the art basedon the embodiments disclosed herein without inventive efforts fallwithin the scope of the present invention.

Although numerous specific details are set forth below to facilitate athorough understanding of the present invention, the invention can alsobe implemented in other ways than those described herein and thoseskilled in the art can make similar forms thereof without departing fromthe spirit of the present invention. Therefore, the present invention isnot limited to the specific embodiments disclosed below.

The present invention will be described in detail with reference to theaccompanying drawings. In order to facilitate the following detaileddescription, the structural sectional views may not be drawn to scalewith parts showing some elements being enlarged. These schematics areprovided merely for example and shall not be deemed as limiting thescope of the invention. Further, in practical fabrication,three-dimensional dimensions of the components, i.e., their lengths,widths and depths shall also be taken into account.

The pixel structure and the OLED display panel incorporating the pixelstructure will be described in details with reference to the embodimentsdescribed below. For the sake of clarity and brevity, the positions ofthe sub-pixels are described with respect to their centers. However, thepresent invention is not limited to this, and it is to be understood bythose skilled in the art that the positions of the sub-pixels may alsobe described with respect to their apexes or other references.

Embodiment 1

FIG. 3 is a schematic showing part of a pixel structure in an OLEDdisplay panel according to a first embodiment of the present invention.FIG. 4 is a schematic illustration of four pixel units in the pixelstructure of FIG. 3.

As shown in FIGS. 3 to 4, the pixel structure of the OLED display panelincludes a plurality of pixel units 110 arranged in an array, eachcomprising three sub-pixels including a first sub-pixel 111, a secondsub-pixel 112 and a third sub-pixel 113. The first sub-pixel 111 isdedicated to the specific pixel unit 110, while the second and thirdsub-pixels 112, 113 are common to four adjacent pixel units. Thisarrangement enables, on the one hand, an increased aperture ratio of thesub-pixels and hence a longer life span of the display device at thesame PPI and design margin, and on the other hand, an increased designmargin and reduced process difficulty at the same PPI and aperture ratiobecause of expanded pixel-to-pixel spacings which are favorable to thereliability of organic emission layer deposition processes utilizingfine metal masks.

As indicated by the dashed square boxes in FIG. 4, every four adjacentthird sub-pixels 113 are arranged to define a quadrilateral, forexample, a square, encompassing one second sub-pixel 112 and fouradjacent first sub-pixels 111. That is to say, every four adjacent thirdsub-pixels 113 surround a second sub-pixel 112 and four sub-pixels 111.Specifically, the four third sub-pixels 113 are respectively located atthe four vertices P1, P2, P3, P4 of the quadrilateral and the four firstsub-pixels 111 are interposed between the third sub-pixels 113 and thesecond sub-pixel 112 so that four pixel units 110 are defined, as shownin FIG. 4, with the second sub-pixel 112 being common to them.

With emphasized reference to FIG. 4, in this embodiment, the secondsub-pixel 112 resides right at a center of the quadrilateral, with thefirst sub-pixels 111 being situated on respective line segmentsconnecting centers of the second sub-pixel 112 and the respective thirdsub-pixels 113. Further, the first sub-pixels 111 may reside on therespective midpoints of the line segments connecting the secondsub-pixel 112 and the third sub-pixels 113. It is a matter of coursethat the positions of the first sub-pixels 111 is not limited to thoseas described above, and they may be, for example, not located on themidpoints of the line segments connecting the second sub-pixel 112 andthe third sub-pixels 113. In fact, the first sub-pixels 111 may bearranged at any positions between the second sub-pixel 112 and the thirdsub-pixels 113 as long as their positions ensure the second and thirdsub-pixels 112, 113 are common to the four adjacent pixel units.

In this embodiment, the first, second and third sub-pixels 111, 112, 113in the pixel structure each assume a quadrilateral shape. In particular,the first sub-pixels 111 are rectangles, and the second and thirdsub-pixels 112, 113 are squares. Further, the long sides of each of thefirst sub-pixel 111 are oriented parallel to the line segment connectingcenters of the second sub-pixel 112 and a corresponding one of the thirdsub-pixels 113, and its short sides extend perpendicular to this linesegment.

Furthermore, the first sub-pixels 111 in every two adjacent pixel unitsare in mirror symmetry with respect to a line segment connecting the twosecond sub-pixels 112 both nearest to both of the specific firstsub-pixels, for example, the imaginary side L1 or L2. Here, the phase“mirror symmetry” means that the two first sub-pixels 111 are of thesame shape but oriented in different directions. Additionally, every twoadjacent second sub-pixels 112, as well as every two adjacent thirdsub-pixels 113, are in exact symmetry to each other. Here, the phase“exact symmetry” means that means that the two sub-pixels are identicalto each other in terms of shape and orientation.

While the first, second and third sub-pixels 111, 112, 113 have beendescribed above as each having a quadrilateral shape as an example, itis to be noted that in other embodiments of the present invention, theymay also have one or more of many other polygonal shapes such astriangular, pentagonal, hexagonal, heptagonal and octagonal, and thelong sides of the first sub-pixel 111 may also not be parallel to theline segment connecting the centers of the corresponding second andthird sub-pixels 112, 113 and may, for example, form a certain angletherewith.

With reference to FIGS. 3 and 4, in this embodiment, the second andthird sub-pixels 112, 113 have the same area, and each first sub-pixel111 has an area smaller than the area of the second and third sub-pixels112, 113. In this embodiment, the first sub-pixels 111 have the smallestarea among the other sub-pixels due to the consideration that each ofthe other sub-pixels is common to the four adjacent pixel units.However, it is noted that the present invention is not limited to anyspecific area of any of the sub-pixels, and the first, second and thirdsub-pixels 111, 112, 113 may have the same area or not, and their areasmay be adjusted according to the coloring requirements of practicalapplications.

With continued reference to FIG. 3, in this embodiment, every firstsub-pixel 111 is spaced apart from each adjacent first sub-pixel 111 bya distance D1, from each adjacent second sub-pixel 112 by a distance D2and from each adjacent third sub-pixel 113 by a distance D3. Every twoadjacent second sub-pixels 112 are spaced apart from each other by adistance D4, and every two adjacent third sub-pixels 113 are spacedapart from each other by a distance D5. As every second sub-pixel 112and the adjacent third sub-pixels 113 are common to the four adjacentpixel units, the total area of the second and third sub-pixels 113 isreduced, allowing greater pixel-to-pixel spacings such as, for example,D2, D3, D4 and D5, at the same PPI and aperture ratio as the traditionalarrangements. This can result in improved reliability of organicemission layer deposition processes utilizing fine metal masks andreduced process difficulty. In this embodiment, the display panel may bestrengthened through placing spacers between the adjacent secondsub-pixels 112 and between the adjacent third sub-pixels 113 withgreater distances D4 and D5 respectively.

In this embodiment, in each odd-numbered row, second and thirdsub-pixels 112, 113 are alternately arranged, for example, along thefirst imaginary line X1 in FIG. 3, with first sub-pixels 111 interposedtherebetween, and each even-numbered row contains only several firstsub-pixels 111 which are arranged, for example, along the secondimaginary line X2 in FIG. 3. In addition, in each odd-numbered column,second and third sub-pixels 112, 113 are alternately arranged, forexample, along the first imaginary line Y1 in FIG. 3, with firstsub-pixels 111 interposed therebetween, and each even-numbered columncontains only several first sub-pixels 111 which are arranged, forexample, along the second imaginary line Y2 in FIG. 3. As such, everytwo adjacent second sub-pixels 112, as well as every two adjacent thirdsub-pixels 113, are not interposed with a first sub-pixel 111. In otherembodiments of the present invention, the second and third sub-pixels112, 113 may be transposed. In other words, in this case, eachodd-numbered row contains only linearly aligned first sub-pixels 111,and each even-numbered row contains second and third sub-pixels 112, 113that are alternately arranged with first sub-pixels 111 interposedtherebetween. Additionally, each odd-numbered column contains onlylinearly aligned first sub-pixels 111, and each even-numbered columncontains second and third sub-pixels 112, 113 that are alternatelyarranged with first sub-pixels 111 interposed therebetween. It is to beappreciated that FIG. 3 shows only part of the pixel structure in theOLED display panel for the sake of brevity, and the pixel structure mayactually include more columns and/or more rows.

In this embodiment, each first sub-pixel 111 is adapted to emit redlight and, to this end, includes an organic emission layer for emittingred light; each second sub-pixel 112 is adapted to emit blue light and,to this end, includes an organic emission layer for emitting blue light;each third sub-pixel 113 is adapted to emit green light and, to thisend, includes an organic emission layer for emitting green light. It isto be appreciated that these light-emitting functions can beinterchanged among the sub-pixels, provided that the first, second andthird sub-pixels 111, 112, 113 include at least sub-pixels for emittingred, green and blue light. For example, in other embodiments, the first,second and third sub-pixels 111, 112, 113 may alternatively emit blue,red and green light, respectively. Similar embodiments are also possibleand will not be described in detail herein for the sake of brevity.

Embodiment 2

FIG. 5 is a schematic showing part of a pixel structure in an OLEDdisplay panel according to a second embodiment of the present invention.FIG. 6 is a schematic illustration of four pixel units in the pixelstructure of FIG. 5.

As shown in FIGS. 5 to 6, the pixel structure of the OLED display panelincludes a plurality of pixel units 110 arranged in an array, eachcomprising three sub-pixels including a first sub-pixel 111, a secondsub-pixel 112 and a third sub-pixel 113. The first sub-pixel 111 isdedicated to the specific pixel unit 110, while the second and thirdsub-pixels 112, 113 are common to four adjacent pixel units.

This embodiment differs from Embodiment 1 only in that the short sidesof the first sub-pixel 111 are parallel to a line segment connectingcenters of the second and third sub-pixels 112, 113, with its long sidesextending perpendicular to this line segment, as shown in FIGS. 5 and 6.

Embodiment 3

FIG. 7 is a schematic showing part of a pixel structure in an OLEDdisplay panel according to a third embodiment of the present invention.FIG. 8 is a schematic illustration of four pixel units in the pixelstructure of FIG. 7.

As shown in FIGS. 7 to 8, the pixel structure includes a plurality ofpixel units 110 arranged in an array, each comprising three sub-pixelsincluding a first sub-pixel 111, a second sub-pixel 112 and a thirdsub-pixel 113. The first sub-pixel 111 is dedicated to the specificpixel unit 110, while the second and third sub-pixels 112, 113 arecommon to four adjacent pixel units.

This embodiment differs from Embodiment 1 only in that the first, secondand third sub-pixels 111, 112, 113 are all squares so that the first,second and third sub-pixels 111, 112, 113 in one pixel unit is in exactsymmetry to those in any adjacent pixel unit. Specifically, the firstsub-pixels 111 in every two adjacent pixel units are in exact symmetrywith respect to a line segment connecting the two second or thirdsub-pixels 112, 113 both nearest to both of the specific firstsub-pixels, for example, the imaginary side L1 or L2 in FIG. 8.

Embodiment 4

An OLED display panel according to this embodiment incorporates thepixel structure according to Embodiment 1, 2 or 3.

In one embodiment, the first, second and third 111, 112, 113 areprovided with power lines for driving individual pixels, for example,gate lines, data lines, driving power lines, etc. In addition, they arealso provided with insulating layers for limiting the individualsub-pixels, for example, pixel limiting layers. Further, in oneembodiment, OLEDs for the individual first, second and third sub-pixels111, 112, 113 are included, each including an anode, an organic emissionlayer and a cathode. The shapes of the individual pixels are defined bythe corresponding power lines, pixel limiting layers and anodes. This iswell-known to those skilled in this art and will not be described ingreater detail for the sake of brevity.

The organic emission layers in the individual pixels of the OLED displaypanel may be fabricated by deposition (e.g., vapor deposition) processesin which masks (e.g., fine metal masks (FMMs)) are utilized. Reducingthe spacings between adjacent pixels can lead to an increase in theaperture ratio of the pixels but a reduction in the reliability of thedeposition processes. On the other hand, while greater pixel-to-pixelspacings can enhance the reliability of the deposition processes, theycan lead to a lower aperture ratio of the pixels. Different from thetraditional RGB pixel arrangements, the present invention allows smallerareas of the sub-pixels. This can enable, on the one hand, a higheraperture ratio of the sub-pixels and hence a longer service life of theOLED display panel at the same PPI and design margin, and on the otherhand, an increased design margin and reduced process difficulty at thesame PPI and aperture ratio because the size-reduced sub-pixels allowgreater pixel-to-pixel spacings which are favorable to the reliabilityof organic emission layer deposition processes utilizing fine metalmasks. Furthermore, spacers may be disposed between every two adjacentsecond sub-pixels, as well as between every two adjacent thirdsub-pixels, which are more distant from each other, to impart higherstrength to the display panel device.

It is noted that the embodiments disclosed herein are described in aprogressive manner, with the description of each embodiment focusing onits differences from other embodiments. Reference can be made betweenthe embodiments for their identical or similar parts.

The foregoing description presents merely a few preferred embodiments ofthe present invention and does not limit the scope thereof in any sense.All changes or modifications made in light of the above disclosure byany person of ordinary skill in the art fall within the scope ofprotection set forth in the appended claims.

1. A pixel structure, comprising a plurality of pixel units arranged inan array, each pixel unit comprising a first sub-pixel, a secondsub-pixel and a third sub-pixel, the second and third sub-pixels beingcommon to four adjacent ones of the pixel units.
 2. The pixel structureof claim 1, wherein adjacent four third sub-pixels are arranged todefine a quadrilateral encompassing one second sub-pixel and adjacentfour first sub-pixels so that four pixel units are formed in which eachof the four first sub-pixels is located between the second sub-pixel anda corresponding one of the four third sub-pixels.
 3. The pixel structureof claim 2, wherein each first sub-pixel resides on a line segmentconnecting centers of its adjacent second and third sub-pixels.
 4. Thepixel structure of claim 1, wherein the first, second and thirdsub-pixels are all polygons.
 5. The pixel structure of claim 1, whereinthe first, second and third sub-pixels are quadrilaterals, hexagons,octagons or any combination thereof.
 6. The pixel structure of claim 5,wherein the first sub-pixel is a rectangle, with each of the second andthird sub-pixels being a square.
 7. The pixel structure of claim 6,wherein short sides of each first sub-pixel are parallel to a linesegment connecting centers of its adjacent second and third sub-pixels;or short sides of each first sub-pixel are perpendicular to a linesegment connecting centers of its adjacent second and third sub-pixels.8. The pixel structure of claim 6, wherein the first, second and thirdsub-pixels in one pixel unit are symmetric to corresponding ones in anadjacent pixel unit.
 9. The pixel structure of claim 1, wherein thefirst sub-pixel has an area smaller than an area of the second and thirdsub-pixels.
 10. An OLED display panel, comprising a pixel structure, thepixel structure comprising a plurality of pixel units arranged in anarray, each pixel unit comprising a first sub-pixel, a second sub-pixeland a third sub-pixel, the second and third sub-pixels being common tofour adjacent ones of the pixel units.